The present invention relates to electronic device cleaning equipment and an electronic device cleaning method, and particularly relates to single-wafer electronic device cleaning equipment and a single-wafer electronic device cleaning method.
Recently, demands for high speed and highly integrated electronic devices are increasing, and miniaturization of electronic devices is being promoted for realizing the demand. In association, cleaning methods for miniaturized electronic devices are in transition from batch cleaning to single-wafer cleaning for enhancing controllability in a region subjected to cleaning.
In a conventional single-wafer cleaning method, as shown in FIG. 10A, after a wafer 1 is placed on a processing face of a cleaning stage 114 located inside a cup 113 with a chuck pin 115 interposed, the obverse face of the wafer 1 is etched in such a manner that a chemical solution is discharged onto the obverse face of the wafer 1 from a chemical solution nozzle 111 while the wafer 1 supported on the cleaning stage 114 is rotated by a rotary table 116. Subsequently, as shown in FIG. 10B, the obverse face of the wafer 1 is cleaned with water by discharging water onto the obverse face of the wafer 1 from a water cleaning nozzle 112. Then, as shown in FIG. 10C, the obverse face of the wafer 1 is dried in such a manner that the wafer 1 supported on the cleaning stage 114 is rotated by the rotary table 116 to shake off water remaining on the obverse face of the wafer 1.
In the above conventional electronic device cleaning method, however, involves the following problems.
Rotation of the cleaning stage 114 supporting the wafer 1 by the rotary table 116 causes friction with air, thereby charging static electricity on the obverse face of the cleaning stage 114. Therefore, the static electricity is present on the processing face of the cleaning stage 114. For this reason, when the wafer 1 having an obverse face on which an insulating film is formed is cleaned, for example, the static electricity present on the processing face of the cleaning stage 114 is induced to the obverse face of the wafer 1 placed on the processing face of the cleaning stage 114 to cause discharge of the static electricity between the insulating film and the chemical solution discharged from the chemical solution nozzle 111.
Accordingly, the discharge of the static electricity forms a hole-like flaw at the obverse face of the wafer 1 (particularly, part of the insulating film where the chemical solution is supplied). As a result, the conventional electronic device cleaning method may lower yield of the electronic device.
For tackling this problem, a method for preventing flaws from being formed at the obverse face of a wafer (particularly, a circuit part of the wafer) is proposed as an electronic device cleaning method (a first conventional example). In this method, after a chemical solution is discharged onto a non-circuit part of a wafer with the use of a chemical solution nozzle capable of moving over the wafer, the chemical solution is discharged onto the circuit part of the wafer (see, for example, Japanese Patent Application Laid Open Publication No. 11-233473A).
According to this method, though a hole-like flaw may be formed by the static electricity discharge in part of the wafer where the chemical solution is supplied first, that is, the non-circuit part at the edge portion of the wafer, it is not formed in the circuit part of the wafer, attaining electronic device cleaning with no lowering of the yield of the electronic device.
Further, there is an electronic device cleaning method using cleaning equipment (see FIG. 11) (a second conventional example) which is aimed at removing the static electricity present on the processing face of the cleaning stage. As shown in FIG. 11, the electronic device cleaning equipment in the second conventional example includes, as main elements, a chamber 210, a chemical solution nozzle 211, a water nozzle 212a, a cap 213, a cleaning stage 214, a chuck pin 215, a rotary table 216, holding means 217, an FFU (fan filter unit) 218, a solution supply line 230, and a valve 231.
In the electronic device cleaning method of the second conventional example, a chemical solution is discharged onto the obverse face of the wafer 1 from the chemical solution nozzle 211 while a solution (a chemical solution, a soda water, or the like, for example) is discharged onto the central part of the reverse face of the wafer 1 from a solution nozzle 230a provided at the solution supply line 230 arranged in the cleaning stage 214. The solution supply to the reverse face of the wafer 1 removes the static electricity present on the processing face of the cleaning stage 214.
The electronic device cleaning method of the first conventional example, however, involves the following problems.
In the electronic device cleaning method of the first conventional example, the chemical solution must be discharged onto the non-circuit part at the edge portion of the wafer from the chemical solution nozzle 211. The selective discharge onto the non-circuit part is difficult, and therefore, the chemical solution is discharged onto part other than the non-circuit part at the edge portion of the wafer 1, that is, the circuit part of the wafer 1, to form a hole-like flaw by the static electricity discharge at the part of the circuit part of the wafer 1 where the chemical solution is discharged. Further, particles may adhere to the obverse face of the wafer 1 by the static electricity discharge.
In addition, in the electronic device cleaning method of the first conventional example, the chemical solution collides with the edge of the wafer 1 and is scattered in discharging the chemical solution, so that the chemical solution cannot be recovered to the cap 213 and the scattered chemical solution adheres to the obverse face of the wafer, resulting in contamination of the obverse face of the wafer 1.
As well, the electronic device cleaning method of the second conventional example involves the following problems.
In the electronic device cleaning method of the second conventional example, as shown in FIG. 11, the solution (a chemical solution, a soda water, or the like, for example) is supplied to the reverse face of the wafer 1 from the solution nozzle 230a provided at the solution supply line 230 arranged at the central part of the processing face of the cleaning stage 214. The solution supply to the edge portion of the reverse face of the wafer 1 is rather difficult.
Accordingly, the static electricity present on the processing face of the cleaning stage 214 (particularly, a range of the processing face of the cleaning stage 214 in the vicinity of the edge of the wafer 1) is removed insufficiently. As a result, the remaining static electricity is induced to the obverse face of the wafer 1 to cause the static electricity discharge between the obverse face of the wafer 1 and the chemical solution discharged from the chemical solution nozzle 211, thereby forming a hole-like flaw at the part of the obverse face of the wafer 1 where the chemical solution is discharged. Further, particles may adhere to the obverse face of the wafer 1 by the static electricity discharge.
As described above, in the electronic device cleaning methods of the first and second conventional examples, the static electricity discharge caused between the obverse face of the wafer and the chemical solution discharged from the chemical solution nozzle causes defects (specifically, flaws and particles), lowering the yield of the electronic device.